differential versus common-mode noise?

There are several sources for noise, including:

1) components - if the outputs are balanced or differential, then they will generate both differential and common-mode noise. If the outputs are single-ended RCA, then common-mode only.

2) ground-loops create common-mode noise by themselves. If you can isolate inputs and outputs of each component from cable ground returns, this is the best solution. Almost as good is putting RF filters in the AC cords earth grounds for each component.

Steve N.
Empirical Audio

Pt - I recommend using USB interfaces with isolation or filtering.

Analog cables can be isolated using transformers such as:
http://www.empiricalaudio.com/products/final-drive

S/PDIF interfaces should use transformers at the DAC input preferably.

Reclockers can be used to both reduce digital jitter as well as isolation, such as:

http://www.empiricalaudio.com/products/synchro-mesh

Its important to break every ground-loop. There should be only earth grounds to each component, not ground connections between components (with cables).

Steve N.
Empirical Audio

Pt - you can find lower cost alternatives. Just do your research.

First thing if you use cable TV or internet is to get a Jensen isolation transformer for the cable.

Steve N.
Empirical Audio